The present invention generally relates to animal husbandry in the form of aquatic animal culturing, aquarium aerators and or to a terminus for a commonly known system of liquid purification or separation, structural installation, closed circulating system for an aquarium.
An unfortunate consequence of the use in aquariums of popular undergravel filter plates, aeration lift tubes and standard exit elbows is that a stream of aeration bubbles is carried by the water flow from the standard exit elbow and subsequently across the surface of the water in the tank. The work of aeration and flow already having been accomplished within the airlift tube, the resultant wide stream of aeration bubbles, although not necessarily unpleasant to look at, serves little purpose.
The surface stream of aeration bubbles, while at the same time as serving little purpose, in fact, can be very harmful to both the function and the appearance of the aquarium as will be explained.
One need only put one's hand within an inch or two of the stream of aeration bubbles flowing across the surface of the water to verify that indeed, upon the continuous implosion of aeration bubbles, a fine spray of water is being impelled continuously into the atmosphere in this vicinity.
This is of little concern in a fresh water aquarium without a light hood, except that there will be a noticeable fine spotting around the edges of the tank. However, in a tank fitted with a light hood, it is inevitable that given a water level within a few inches of the top rim of the tank, that the glass or Plexiglas underside of the light hood will become constantly wetted from the never ending fine spray of water. Furthermore, it is all too likely that a thick, dark green film of algae, more than sufficient to completely block the intended light coming from the fluorescent tubes in the light hood, will form in this environment due to the light, warmth and constant fine spray of water onto the bottom of the light hood. As well, even more algae, although not as thick, will likely form on the underside of the horizontal structural surface that is found on the top of all Plexiglas tanks.
It is unacceptable to move the light hood further away, as this would diminish the often hard won illumination level. And there is not much you can do about the aeration spray landing on the underside of the horizontal surface that is found on the top of all Plexiglas tanks, altogether, other than lowering the water level drastically to what would be an unattractive level and also make waste of the water capacity of the aquarium.
In a saltwater aquarium these problems are compounded by a puddle of wet encrusted salt forming around the wet undersides of the light hoods, which since they are sitting on the Plexiglas horizontal surface on the top of the tank, carry a substantial quantity of the water sprayed onto the underside of the light hood onto the top surface of the Plexiglas itself, which ends up creeping across the surface and eventually encrusting down the sides of the tank and in particular forming in very large quantities behind the tank where one is not likely to see the accumulated salt, or even reach it, if the tank is sitting against a wall.
Even in a saltwater tank that is glass and has no light hood, water spray from the implosion of aeration bubbles lands on the filter tubes, airline tubes, tank top edges and any nearby walls. This small amount of fine spray of saltwater actually making its way outside of the tank, while hardly noticeable in a fresh water tank, eventually leads to huge amounts of encrusted salt deposits on the tank top edges, tank sides, all nearby aeration and filter tubes and on the wall when enjoying the use of a saltwater aquarium.
Aerating smaller containers without any airlift tubes, such as might be done to raise brine shrimp, creates even heavier saltwater spray from the implosion of aeration bubbles.
Clearly, since the surface stream of aeration bubbles serves little purpose, it would be desirable to eliminate the thousands of imploding aeration bubbles making their insidious way across the surface of the water, and yet still enjoy the benefits and ample aeration of an undergravel filter and aquarium airlift tube.
Numerous devices designed as a terminus for a stream of aerated water from an airlift tube have been disclosed in prior art. In all cases, the terminus devices described have been for the purpose of increased filtration of the water and not merely to contain spray, if not just a simple elbow. U.S. Pat. No. 2,676,921 to Vansteenkiste (1954) contains an unusually complete references cited section in regard to the early progression of airlift tubes and closed circulating systems for use in aquariums.
Furthermore, certain devices such as most protein skimmers, provide some means for the separation of aeration bubbles from the water stream, usually a simple half wall or else a downdraft tube, since by their nature the foam must be collected in one spot. Some even utilize extra aeration bubbles in a separated airlift tube for the purpose of creating a counter flow in the water. In any case, such devices would not work for containing the aeration spray from a commonly known standard airlift tube, and the models that separate aeration bubbles from the exit stream require a water pump.
U.S. Pat. No. 3,778,976 to Pond (1973) discloses a degasser having baffle means to cause the water to flow downwardly in a zigzag path. The stated purpose, however, is to degas harmful gasses from the water and not merely to contain the aeration bubbles in said degasser, although it will do both. This device requires a water pump and would also not function to contain aeration spray from a standard airlift tube.
U.S. Pat. No. 5,275,123 to Geung (1994) discloses a separate upright column, having an open top in combination with a water pump for spraying water for the express purpose of containing aeration bubbles in said upright column. Although effective, this design would also not work without a water pump, relies on downward water direction water flow, and will not function to contain aeration bubbles if the flow of water is in an upward direction, as with a standard airlift tube.